MOSCOW -- In a case with far-reaching political implications, a leader of the anti-Semitic Russian nationalist movement Pamyat was sentenced to two years in a labor camp yesterday for shouting insults and threats against Jews at a writers' meeting in January.

The conviction of Konstantin Smirnov-Ostashvili for "inciting inter-ethnic hatred and enmity" is the first of its kind in Russia, legal experts here said.

It represents an unprecedented intervention of the Soviet criminal justice system in defense of Jews and against the recent resurgeance of public anti-Semitism, which has prompted tens of thousands of Soviet Jews to emigrate to Israel and the United States.

"Even in South Africa, such a thing couldn't be!" the short, bald, 54-year-old Smirnov-Ostashvili shouted as Judge Andrei Muratovread the sentence in Moscow City Court. "You see what kind of democracy this is? When they kill Russians, there's not even a trial!"

Several dozen supporters jumped up and began to chant, "Shame! Shame!" as police led Smirnov-Ostashvili from court.

Yuri D. Chernichenko, a writer and member of parliament who spoke for the prosecution, said the verdict in this closely watched case was of historic importance.

"It's a first in the history of Soviet jurisprudence, which in the past has been used to repress millions simply because of their nationality," he said. "Now the law is turning around and offering people protection, irrespective of their nationality."

Leonid Nikitinsky, legal affairs writer for the newspaper Komsomolskaya Pravda, hailed the conviction but said he feared the two-year sen

tence would turn Smirnov-Ostashvili into a martyr.

"I'm afraid that by locking him up they'll make him into a popular hero and inadvertently help his cause," Mr. Nikitinsky said.

Mr. Chernichenko disagreed.

"That's not important," he said of the possibility the sentence might backfire. "Evil is evil. Let the law be enforced."

Smirnov-Ostashvili faced a maximum possible sentence of five years for violating Article 74 of the Russian Federation criminal code. Prosecutors had asked for the two-year sentence.

Smirnov-Ostashvili, himself half-Russian and half-Georgian, is a leader of one of several small, extreme Russian-chauvinist organizations using the name Pamyat, the Russian word for "memory." They have become active under the new tolerance of public political activity over the last four years and regularly hold rallies and meetings in Moscow, Leningrad and other cities.

Their ideology combines tradition al Slavophilism with elements of Hitlerite fascism, alleging that a "Jewish-Masonic conspiracy" is responsible for the 1917 revolution, the Stalinist terror and the general deterioration of the country. In recent months some extremists have begun to call openly for violence against Jews.

Smirnov-Ostashvili led a group of Pamyat activists who burst into the headquarters of the Soviet Writers' Union in central Moscow in January and disrupted a meeting of a liberal writers' group known as April.

Screaming into a megaphone, Smirnov-Ostashvili threatened those present: "Today we come with megaphones. Next time we'll come with submachine guns." He and others scuffled with members of April and yelled anti-Jewish slurs.

Caught on videotape, the incident was shown on national television and widely discussed as a possible prelude to a revival of anti-Jewish pogroms, widespread in the Russian Empire in the 19th century and the first two decades of this century.

Particular concern arose from the fact that the Pamyat group was able to enter the exclusive Writers' Union building unimpeded, and that police responded slowly and unenthusiastically when called. Many of the writers present suspected that Smirnov-Ostashvili had patrons in the police, the KGB security agency and the Communist Party.

Under intense public pressure, Moscow prosecutors opened a criminal case against Smirnov-Ostashvili. His trial, which has continued off and on for months, received extensive coverage from the Soviet media.

Yesterday, nearly half the approximately 150 people squeezed into the courtroom under heavy security were reporters and photographers. Five television cameras pointed at supporters of the defendant as they defied police warnings and unfurled posters saying "Court, Do You Serve the Law or Zionism?" and "Down with the Unfair Court."

In front of the courthouse, Pamyat activists and sympathizers denounced the verdict as a violation of human rights.

Sergei, a 24-year-old student said that if the trial was intended to deter anti-Semites, it will backfire. "It will be worse, not better, for Jews here, because this is going to make Russians very angry," he said.